Tribological behavior of diamond-reinforced Fe-Co composite by - PDF document

18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS Tribological behavior of diamond-reinforced Fe-Co composite by Taguchi method K. Emre Öksüz 1 , M. Şimşir 1, Y. Şahin 2* 1 Cumhuriyet University , Metallurgical and Materials Engineering Department, 58140, Sivas/Turkey, 2 Gazi University, Manufacturing Engineering Department, Faculty of Technology, 06500 Ankara/Turkey * Corresponding author(ysahin@gazi.edu.tr) Abstract. Tribological behavior of diamond-reinforced Fe-Co composites was studied. SN ratio and ANOVA were employed to investigate the influence of parameters like, abrasive size, load, distance and hardness. The load factor was the major parameter, followed by abrasive size. The percent contributions are abrasive size (32.17 %), hardness (11.30 %). Keywords : Fe-Co matrix; Diamond tool; Powder metallurgy; Tribological behavior . 1. Introduction reinforcement in the production of metal matrix Diamond has the highest thermal conductivity and composite while Co metal was a binder with a good low coefficient of friction, and shows superior wet ability. Fe is also used as a filling material mechanical properties such as bulk modulus, tensile because of its lower-cost. The concentration of stress and hardness. High hardness and wear diamond grits in the composite was kept at about resistance result in good surface finish and long tool 20%. Fe-(15-35-55wt. %Co)-bronze 10wt. %- life [1]. Therefore, diamond tools are widely used diamond 20wt. %. A Co, Fe powder and diamond for difficult-to-cut materials like Al-Si alloys, fiber grits with an average particles size of 400 mesh, reinforced composite or stone, concrete. The matrix 85/15 mesh and -40/+50 mesh powders were used in the most diamond tool, is a cobalt alloy since selected as the starting material. Hereafter, these are it combines with diamond grits good chemical denoted by C1 (Fe-15Co-10bronze-20diamond), C3 compatibility at the processing temperature. (Fe-35Co-10bronze-20diamond), and C5 (Fe-55Co- However, the price of Co is subjected to great 10bronze-20diamond). variations [2]. This is the main reason behind efforts to replace Co with other metals such as Co-bronze, In the production of composites, Fe-Co-bronze- Fe-bronze, Tin-Co, Fe-Co, Fe-Cu, Fe-Co-Cu diamond- was blended in T2 turbula mixture at materials [3, 4]. The properties of diamond abrasive about 45 min. The mixture per composition was put and the adhesion between the diamond grits and in carbon moulds 24X10X10 mm dimension were bond determine properties of diamond tools [5]. This cold compacted, and then hot zone was evacuated to also depends upon composition of metal powders, remove the air from the chamber atmosphere, and their sizes and distributions, processing temperature sintered by hot pressing of Fritsch DSP 510 type and times [6]. The aim of the present study is thus, machine under nitrogen atmosphere. The sintering temperature was about 800 o C under a compression to investigate the wear behavior of diamond impregnated composite by changing the matrix of 25 MPa. Total sintering time was about 15 min. composition based on Fe/Co ratio and B 4 C powder addition. The wear parameters were abrasive size (A), material hardness (B), load (C) and sliding distance 2. Experimental study (D) and their levels indicated in Table 1. An L18 Fe-Co-Bronze based diamond with and without B 4 C orthogonal array was chosen. reinforcement composites were produced by hot as pressing method. Diamonds were used

18 th International Conference on composite materials Table 1. Control factors and their levels for diamond found that the sliding distance was the most reinforced MMCs. effective parameter for Al/SiCp and Al/Gr matrix Levels Abras. Hardness Applied Sliding composites, which is followed by the load. The least size, , BHN load, N dist., m weight loss is recorded during 7th test run when the µm process parameters were at first level of A, 3rd level 1 22 µm 76.6 5 24 of B, first level of C and D factor. It is followed by 2 68 µm 79 15 48 8 th , 4 th and 1 st run. 3 - 84 25 72 M a in E f fects P lo t for M ea n s 3. Results and discussion A B 0 .0 2 0 3.1. Main effects plot 0 .0 1 5 Fig.1a indicates the main effects plots of the weight Mean of Weight Loss (g) loss of composites for the means. The average values of weight loss for each parameter at levels 1, 0 .0 1 0 2 and 3 were calculated and were shown in Fig.1. Optimal testing conditions of these control factors 22 68 76.6 79.0 84 .0 could be determined from this graph. The best C D 0 .0 2 0 weight loss value was at the lower mean value in the response graph. It was clear from Fig.1 that the 0 .0 1 5 weight loss was minimum at the 1st level of parameter A, 3rd level of parameter B, 1st level of parameter C and lastly 1st level of parameter D. It 0 .0 1 0 was evident that the load (C) had the greatest effect on the optimal testing conditions. This might be 5 1 5 2 5 24 48 72 because SiC abrasive did not have an ability to dig a) Mean out of diamond powders in its place to remove it. On the other hand, the level of a factor with highest S/N M a in E ffec ts P lot fo r S N r a tios ratio is the optimum level, as shown in Fig.1b. A B Hence, the optimum levels of the factors are A 1 , B 3 , 4 2 C 1 and D 2 . 4 0 Mean of SN ratios (dB) 3 8 Table 2 shows experimental lay out and results with calculated S/N ratios for weight loss of the 3 6 composites. The control factor with the strongest 3 4 influence is detected by difference value. It can be 2 2 6 8 7 6 .6 7 9 .0 8 4 .0 seen in Table 2 that the strongest influence is exerted C D by C and A, respectively. The weight loss obviously 4 2 increases as load increases from 5N to 25N, 4 0 followed by the abrasive particle size from 400 mesh 3 8 ( ≈ 22 µm) to 180 mesh (( ≈ 68 µm ). In addition, weight loss increases slightly with the B and D factor. 3 6 These effects, however, much lower compare to 3 4 those of C and A factor. The results are good 5 1 5 2 5 2 4 4 8 7 2 agreement with Mondal et al. [7], Prasad et al. [8] b) S/N ratio and Basavarajappa et al. [9]. However, previous works by Fernandez et al. [10], Sahin [11] indicated Fig.1. Effects of main parameters on the weight loss of that abrasive size was the more effective on wear diamond-reinforced MMCs. a) Abrasive size, b) rate of the samples. Basavarajappa et al. [9] also Hardness, c) Load, d) Sliding distance.